The region of the atmosphere that extends from ground level to roughly 11 kilometers (7 miles) above sea level

stratosphere

The region of the atmosphere that spans altitudes of roughly 11 kilometers to 48 kilometers (30 miles)

mesosphere

The region of the atmosphere that spans altitudes of roughly 48 kilometers to 80 kilometers (50 miles)

jet streams

Narrow bands of high-speed winds that circle the earth, blowing from west to east.

heat

Energy that is transferred as a consequence of temperature differences

temperature

A measure of the energy of random motion in a substance's molecules

thermosphere

The region of the atmosphere between altitudes of roughly 80 kilometers and 460 kilometers

exosphere

The region of the atmosphere above an altitude of roughly 460 kilometers

ionosphere

The region of the atmosphere between the altitudes of roughly 65 kilometers and 330 kilometers, where the gases are ionized.

Why don't you feel like 14.7 pounds of pressure are pressing on every square inch of you?

For every pressure pushing one way, there is an equal pressure pushing the opposite way, so you don't feel anything.

Why do most barometers use mercury instead of water?

Water is lighter than mercury, so for a certain atmospheric pressure, the column of water would have to be much taller before its weight was equal to the atmospheric force, while the mercury column would be shorter. It makes the barometer a practical size to use mercury.

What is normal barometric pressure, and what does it mean?

Normal barometric pressure is 29.9 inches, which means that the mercury column is 29.9 inches high.

Is atmospheric pressure typically more or less at the top of a mountain as compared with sea level?

Less, because there is less atmosphere to press down.

Does the composition percentage-wise of gases in the atmosphere vary within the homosphere?

No, the percent composition is the same everywhere in the homosphere - always 78%nitrogen, 21%oxygen, etc. This is why there is the prefix "homo", meaning "same."

Does the amount of air vary within the atmosphere?

Yes, the actual amount of gas molecules in a given volume of space decreases as you get further from the earth's surface - the air gets "thinner." What air there is, however, still has 78% N, 21%O, etc.

Is the composition of the heterosphere uniform?

No, that is why it is called "hetero." The lower part of the heterosphere is mostly oxygen, while the upper part is mostly helium, then hydrogen.

The troposphere, stratosphere, and mesosphere all make up what layer of the atmosphere?

homosphere

tropopause

boundary between the troposphere and stratosphere

stratopause

The boundary between the stratosphere and the mesosphere

mesopause

boundary between the mesosphere and heterosphere.

In general, what happens to atmospheric pressure as altitude increases (even within the homosphere?)

Atmospheric pressure decreases with increasing altitude.

In what layer does most weather occur?

troposphere

The percent of oxygen in the air is 21% both at the top of Mount Everest and in New York City. Why, then, do people need extra oxygen supplies at the top of Mt. Everest but not in NYC?

While the percent of oxygen is the same compared to other gases, the actual amount of oxygen is much less at the top of a mountain than at sea level (less gravity to hold gases there.)

temperature gradient

The gradual decrease in temperature as altitude increases within the troposphere. This is why there is still snow at the tops of mountains even in the summer. This does not hold true once you reach the stratosphere.

Are there significant amounts of weather phenomena or water vapor in the stratosphere?

No

Where do jet streams occur, and what do they do?

They occur in the lower part of the stratosphere and uppermost portions of the troposphere. Jet streams blow on top of clouds, steering storms and affecting high and low atmospheric pressure areas.

What happens to the temperature gradient in the stratosphere?

It reverses, getting warmer as you go higher in the stratosphere. This occurs because the ozone layer is in the stratosphere, and the energy that ozone absorbs from its interaction with UV light warms this layer up.

What happens to the temperature gradient in the mesosphere?

It reverses once again, getting colder as you go higher. This happens because there is no significant ozone in the mesosphere.

What happens in the mesosphere that we can see periodically on Earth?

Despite the fact that the air is very thin in the mesosphere, there is enough air to cause friction when meteors enter it. We see the meteors burning up as a result of this friction.

air resistance

friction between an object and the molecules of air through with it moves. Air resistance decreases as altitude increases, because there is less air to interact with.

What is the relationship between air resistance, airplane speed, and the layers of the atmosphere?

Airplanes use less fuel when flying at higher altitudes, because of the decreased air resistance. Also, engines are more efficient at lower outside temperatures. However, it takes a lot of fuel to fight gravity and pull away from the earth's surface.

What happens to molecules when energy is added to them?

They move faster and harder.

What happens when a thermometer is placed in a substance whose molecules are moving more slowly than the thermometer?

Energy is transferred from the thermometer to the substance, causing the temperature registered on the thermometer to go down.

What happens when a thermometer is placed in a substance whose molecules are moving more quickly than the thermometer?

Energy is transferred from the substance to the thermometer, causing the temperature registered on the thermometer to go up.

Why does the temperature go down as altitude increases in the troposphere?

The amount of greenhouse gases decreases, thus decreasing the amount of molecules that can absorb radiated energy.

Does the amount of greenhouse gases increase in the stratosphere?

No, it decreases.

What is responsible for the increase in temperature in the stratosphere?

The ozone layer is in the stratosphere. When ozone absorbs UV light, it also absorbs its energy, increasing the temperature in the stratosphere.

Why does temperature go down again at the stratopause?

The levels of ozone fall off again.

Why is there concern about an "ozone hole" in the atmosphere?

If there is less ozone to absorb UV light, there would be larger amounts of UV light reaching the earth's surface and damaging living beings.

Where and when does the "ozone hole" occur?

It occurs over Antarctica during the months of August through November.

Is the ozone hole really a hole?

No, it is just a decrease in the amount of ozone from the areas around it, making a relative hole.

What is a polar vortex, and what does it have to do with the ozone hole?

A polar vortex is a wind that blows across the South Pole during the months of August-November, causing persistent cold temps and an upward wind. This makes water freeze into tiny ice particles, which are carried upward into the stratosphere. Sometimes these ice particles trap CFCs in them, and chemical reactions occur on the surface of the ice particles, causing chlorine to be released from the CFCs, releasing chlorine that can destroy ozone.

Why does the ozone "hole" disappear during the rest of the year?

The polar vortex, which is responsible for bringing CFCs up to the ozone layer, disappears.

CFCs

Chlorofluorocarbons, a class of substances used for refrigeration, surgical sterilization, and firefighting agents. They are incredibly useful and completely nontoxic.

When the ozone "hole" was first discovered, were CFCs in wide use?

No. Therefore, they cannot be the sole cause of the "ozone hole."

Has the ozone "hole" gotten worse over time?

Yes, it has. However, during the rest of the year, ozone levels remain unchanged from the past.

What is the probable effect of the ozone "hole" on human health.

Very minimal. Since it is centered over an area where very few people live and is present for only 4 months of the year, its potential for human impact is very small.

What is the potential effect of a CFC ban on human health?

Since less efficient means of fire fighting, refrigeration, and sterilization will have to be used, there is potentially a large impact on human health.

Why is it irrelevant to argue that only 0.1% of chlorine-containing molecules released into the atmosphere come from human sources?

While it is true that it is just a tiny fraction of the overall produced at ground level, because of their relative inertness, CFCs represent the majority of molecules that survive the trip up the polar vortex. Other sources are so reactive that they interact with other things on the way up, not making it to the ozone layer. By the time you reach the ozone layer, 81% of the chlorine is from human sources.

What are the two layers of the heterosphere?

Thermosphere and exosphere.

What is the origin of the name "thermosphere"

In the thermosphere there are very few molecules, so the temperature is very low. However, the average energy of each molecule that is there is very high, thus the name "thermosphere" for a layer that has low temperatures.

How do the numbers of protons and electrons in a typical atom compare?

They are equal, yielding an atom that is electrically neutral.

proton

positively charged particle in an atom

electron

negatively charged particle in an atom

How is the sun responsible for the ionosphere?

Various types of radiation from the sun collide with atoms in the ionosphere, in the process removing electrons from atoms there, changing those atoms into ions.

Ion

an electrically charged atom.

How is the ionosphere useful to humans?

Certain radio signals bounce off the ionosphere, making their signals available to large parts of the world.

How far can AM and FM radio station signals travel?

A few hundred miles.

How far can shortwave radio signals travel?

Because they bounce back off the ionosphere, they can travel virtually around the world.

What causes the auroras in the sky?

High energy collisions between ionized particles in the ionosphere produce a lot of energy, some of which is emitted as light. Most of these collisions occur over the North and South Poles, which is why the auroras are visible in the far north and far south.